util: print all errors in a log

CID 154076 (#1 of 1): Unchecked return value from library (CHECKED_RETURN)
1. check_return: Calling setsockopt(sk, 6, 1, &val, 4U) without checking return value. This library function may fail and return an error code.

Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>